The microstructure and mechanical properties of powder metallurgical Al7075 alloy modified by the addition of 1 wt. % Zr were studied. The gas atomized powder was consolidated by spark plasma sintering (SPS) to a fully dense compact. The powder particles of the typical size below 50 μm had a cellular to columnar or equiaxed dendritic microstructure (the size in the order of μm) with a large fraction of intermetallic phases at the boundaries. During sintering at 500 °C for 3 min the grain structure remained nearly unchanged. Optical microscopy revealed a bimodal microstructure. The grain size remained unchanged during annealing at even 500 °C for 10 hours. The microhardness of the SPS compact material was 150 HV. The annealing at 500 °C for 10 hours resulted in a decrease of microhardness to 110 HV. Natural aging at room temperature gradually enhanced the microhardness to its initial value. Tensile tests performed on naturally aged samples at room temperature revealed a brittle behaviour. Ductility of 14 % was found at 500 °C. Both the measurements of the strain rate sensitivity parameter m and results of light and scanning electron microscopy revealed the operation of grain boundary sliding.Keywords: Al7075 alloy, zirconium, spark plasma sintering, powder metallurgy
© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.